During integrated circuit manufacture, semiconductor wafers used in semiconductor fabrication typically undergo numerous processing steps, including deposition, patterning, and etching steps. Details of these manufacturing steps for semiconductor wafers are reported by Tonshoff et al., “Abrasive Machining of Silicon”, published in the Annals of the International Institution for Production Engineering Research, (Volume 39/2/1990), pp. 621-635. In each manufacturing step, it is often necessary or desirable to modify or refine an exposed surface of the wafer in order to prepare the wafer for subsequent fabrication or manufacturing steps. For example, semiconductor wafers having shallow trench isolation (STI) structures require planarization of the dielectric material prior to further processing
One method of modifying or refining exposed surfaces of wafers employs processes that treat a wafer surface with a slurry containing a plurality of loose abrasive particles dispersed in a liquid. Typically this slurry is applied to a polishing pad and the wafer surface is then ground or moved against the pad in order to remove or take off material from the wafer surface. Generally, the slurry also contains additives that chemically react with the wafer surface and which may provide CMP process selectivity, for example, “stop on nitride” selectivity. This type of process is commonly referred to as a slurry-based chemical-mechanical planarization (CMP) process.
One limitation of slurry-based CMP processes, however, is that the slurry abrasive processes must be carefully monitored in order to achieve a desired wafer surface topography and avoid dishing of the wafer surface. A second limitation is potential for scratching the wafer surface associated with use of loose abrasive slurries. Another limitation is the mess associated with slurries, and the large number of particles that must be removed from the surface of the wafer and disposed of following wafer treatment. Handling and disposal of these slurries generates additional processing costs for the semiconductor wafer fabricator.
An alternative to slurry-based CMP processes uses an abrasive article to modify or refine a semiconductor surface. A CMP process that uses abrasive articles has been reported, for example, by Bruxvoort et al. in U.S. Pat. No. 5,958,794 and by Kaisaki et al. in U.S. Pat. No. 6,194,317. The disclosed abrasive articles may have a textured abrasive surface that includes abrasive particles dispersed in a binder. In use, the abrasive article may be contacted with a semiconductor wafer surface, often in the presence of a fluid or working liquid to provide a planar, uniform wafer surface. Use of an abrasive article overcomes some, but not all limitations associated with CMP slurries. The art continually searches for new and improved abrasive compositions and methods for slurry-free CMP processes.